Low BMI and falling BMI predict HIV-associated tuberculosis: a prospective study in Tanzania

Area of Science:

• Infectious Diseases
• Immunology
• Public Health

Background:

• Low body mass index (BMI) is a recognized risk factor for tuberculosis (TB) in non-human immunodeficiency virus (HIV) infected individuals.
• Prospective studies investigating the link between BMI and the risk of HIV-associated TB are lacking.

Purpose of the Study:

• To prospectively examine the association between baseline BMI and changes in BMI with the risk of developing TB in HIV-infected adults.
• To determine if BMI can predict TB incidence in a population with HIV.

Main Methods:

• Prospective cohort study involving HIV-infected adults with CD4 counts ≥ 200 cells/μl.
• Baseline and Year 1 Body Mass Index (BMI) were measured in participants receiving a placebo in a TB vaccine trial.
• Statistical analyses, including multivariate regression, were used to relate BMI parameters to TB development.

Main Results:

• 92 TB cases were identified among 979 participants over a mean follow-up of 3.2 years.
• Individuals who developed TB had significantly lower baseline BMI and a greater decline in BMI from baseline to Year 1 compared to those who did not develop TB.
• Lower baseline BMI (HR per kg/m(2) 0.94) and a decrease in BMI (HR per kg/m(2) 0.79) were independently associated with an increased risk of TB. A baseline BMI < 17 kg/m(2) significantly increased TB risk (HR 3.72).

Conclusions:

• Low baseline body mass index (BMI) is a significant predictor of tuberculosis (TB) risk in HIV-infected individuals.
• A declining BMI over the first year of observation further increases the risk of developing TB in this population.
• BMI serves as a valuable clinical indicator for TB risk stratification in people living with HIV.